Implantation of bone marrow beneath the kidney capsule results in transfer not only of functional stroma but also of hematopoietic repopulating cells.

Renal ossicles are ossified structures developed after the implantation of a bone marrow (BM) plug beneath the kidney capsule. The authors have investigated the origin of the hematopoietic cells in murine renal ossicles by conducting sex-mismatched implants into Ly-5 congenic mice. BM plugs from transgenic mice provided additional genotypic tracers. Flow cytometry analyses on nonadherent cells from long-term cultures established with ossicles excised at 17 to 40 weeks postimplantation evidenced the presence of 5% to 70% of donor-derived myeloid cells. The genetic analysis of the day 12 colony-forming unit (CFU-S(12)) population in ossicles excised at 10 to 40 weeks postimplantation revealed that 16% to 93% of the colonies were of donor origin. Moreover, we describe for the first time the presence of long-term repopulating cells of donor origin in ossicles excised at 10 to 19 weeks postimplantation.